ArrayList in Java Programming

This article provides a comprehensive overview of ArrayList in Java programming language along with example programs.

Introduction to ArrayList

 ArrayList class uses a dynamic array for storing a list of elements. It is inherited from AbstractList class and implements List interface. Following are some important points about ArrayList:

• ArrayList can contain duplicate elements.
• ArrayList size varies. When number of elements increase, size of ArrayList increases automatically, and when number of elements decrease, size of ArrayList also decreases.
• ArrayList preserves the insertion order of elements.
• ArrayList class is non-synchronized.
• ArrayList allows random access of elements as it uses an array to store elements.
• ArrayList is slow when insertion or deletion of elements is performed.

ArrayList Constructors

Following constructors are supported by the ArrayList class:

ArrayList Methods

Following are some of the most frequently used methods of ArrayList:

ArrayList Example

Following is an example program which demonstrates adding elements to a ArrayList and displaying them using a for  each loop:

import java.util.*;

public class Driver
{
	public static void main(String[] args)
	{
		ArrayList<String> friends = new ArrayList<String>();
		friends.add("Ramesh");
		friends.add("Mahesh");
		friends.add("Suresh");
		friends.add("Dinesh");
		friends.add("Ganesh");
		for(String item : friends)
		{
			System.out.println(item);
		}
	}
}

Output for the above program is as follows:

Ramesh
Mahesh
Suresh
Dinesh
Ganesh

Suryateja Pericherla

Suryateja Pericherla, at present is a Research Scholar (full-time Ph.D.) in the Dept. of Computer Science & Systems Engineering at Andhra University, Visakhapatnam. Previously worked as an Associate Professor in the Dept. of CSE at Vishnu Institute of Technology, India.

He has 11+ years of teaching experience and is an individual researcher whose research interests are Cloud Computing, Internet of Things, Computer Security, Network Security and Blockchain.

He is a member of professional societies like IEEE, ACM, CSI and ISCA. He published several research papers which are indexed by SCIE, WoS, Scopus, Springer and others.